Method of testing wax



Patented Aug. 7, 1951 METHOD OF TESTING WAX Karl A. Fischer, Washington, D. 0.

No Drawing. Application May 18, 1948, Serial No. 28,914

11 Claims. (01. Ii-432) (Granted under the act oi March 3, 1883, II

amended April 30, 19a; 3'" O. G. 757) The invention described herein, ii patented, may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a method for the determination of the oil content in waxes. More particularly the invention is concerned with the addition of an oil soluble and crystallizable coloring matter tomolten parafllnic waxes and subsequent crystallization of the wax with or without recrystallization of the coloring matter.

It has been discovered that paraffln crystals, in contrast to other crystalline material, have no tendency to include oil or liquid. Particularly,paraflin waxes in molten form have been found to be a solubilizing agent for coloring matter in the nature .of sudan dyes and alizarin dyes. Upon crystallization, however such coloring matter is not retained by the paramn crystals which also excludes oils. The oil which may be contained by a molten wax composition, however, tends to adhere to the surface of the wax crystals in minute quantities unless the crystals are thoroughly and completely washed. In the usual practice of wax production it has been difllcult to determine the freedom of wax from oils thereby causing the wax in many instances to retain an oil contamination or unknown value.

It is, therefore, an object of this invention to provide a means for determining the oil content oi waxes.

It is another object of this invention to provide a method of determining or measuring the relative purity of warm material by incorporating in a liquid waxy composition an oil-soluble dye stufl or coloring matter which is soluble in the liquid or uncrystallized wax composition but insoluble in crystallized wax, and by reason 0! the solubility of the coloring agent in the components oi the liquid wax composition and the solubility of the coloring agent in a wax component of the composition, when the wax is in its crystallized state, evaluating the color change by exclusion of the coloring agent from the wax in its state.

It is a turther object of this invention to provide a method for determining the freedom of waxes from oils without the need for microscopic examination.

The method of utilizing a dye stui! which is oil soluble and soluble in molten wax involves the admixture of a minute quantity of crystallizable dye stun or other similar crystallizable coloring matter with a small sample of the molten wax.

crystal stage which leaves the color substance either in a crystallized form, it no oil is present. or in solution in the oil.

In the practice 0! this invention, it ha been found that a sudan dye stufl, for example, sudan red in the very minute proportion of 0.05 to 0.10% may be mixed with and is soluble in a very small sample of melted wax. This dye stuff is very intense and has the property of being soluble in the wax while it is in a molten stage and also in the oil content of the wax, if any. A small sample of the mixture, as a drop. may be placed upon a glass slide and this sample thereafter cooled to crystallize the wax and dye stud material without solidifying the mixture of dye stuii and oil. it oil is present. It oil is present with the wax, it will keep the dye stuff in solution in the form of colored spots with undefined boundary. The shade of this color will vary in propor- 59 tion to the oil content and may be used with a prepared table of standard wax samples having known oil contents on a comparative basis and tabulated in wax percentages or oil percentages as desired.

as strikingly. the color shade of the dye stud is different from that of the; dissolved dye stun. For example, in the absence of oil. sudan red crystallizes and the crystals have a bluish-fuchsia red tint whereas it retained in solution the coloring is a yellowish-salmon red tint. Various quantitie of oil content will likewise cause graduated respective shades or tints with similar and other oil soluble and crystallizable coloring matter in the nature of the dye stuii' series indicated.

Likewise, for example, an alizarin dye stufl as aiizarin-irlsoiblue will show a color effect which may be readily determined. lls herein set forth. the oil-soluble sudan and alizarin coloring agents. soluble in molten wax and insoluble in solidified wax are applicable for making determinative color readings of waxy compositions.

For a definition of sudan dyes, reference is made to Hackh's Chemical Dictionary, 3rd ed.. 1944. page 815, listing the following sudan dyes:

Sudan III, sudan red: aminoazobenseneazo-betanaphthol Sudan IV, Scarlet Red; toluene-azo-toluene-azobeta-naphthol (at page 758) The wax and coloring matter is then cooledto a These sudan dyes are thus characterized by a beta-naphtha] group attached to another aromatio group by an azo (N=N) linkage.

Alizarin-irisolblue is listed in the Colour Index the Society of Dyers and Colourists, 1924, as No. 1073 alizarin-irisoi D, R, with the structural formula BOINI C 0 EN Alizarin is defined in Health; Chemical Dictionary, 3rd ed., 1944, page 31, as an anthraquinone derivative. The anthraquinone group characterizes the alizarin-irisolblue and 25 alizarin dyes tabulated on the same page of the chemical dictionary. The term "alizarin dye" is thus used in the sense of anthraquinone derivative dyes.

The color shades or tints produced, particularly when using a brilliant or vivid dye stuff for making comparison tests may be observed by the eye without requiring microscopic examination. However, in making these tests some care is necessary, as in all crystallizing problems, in keeping the time constant between preparation of the sample and making an examination either with or without a microscope as desired. Thi time interval requires approximately from five to ten minutes before an evaluation of a reliable result can be obtained. Further during this time interval and during the examination suitable low temperatures are maintained for the crystalline material to keep it in the crystalline stage.

Preferably as indicated only a trace of the dye stuff or coloring agent is added to the wax material undergoing investigation. As heretofore indicated, examination of the crystallized substance indicates by color separation, the presence or non-presence of oil. It desired, the wax crystals may be observed under a microscope and it will be seen that the dye or coloring material is resting beside the entirely colorless parai'lln crystals.

It has been discovered that the above method may be utilized particularly to estimate the percentage of small quantities of oil in brown coal tar paraflln and mineral oil waxes as with high molecular ceresinic waxes results may be comparative but are not conclusive. For example, the method is preferably used with relatively purifled wax material of the character described. which may contain from 5% to no oil. A wax product having larger percentage of oil will color the field of vision, due to its being relatively unifoymly dispersed over the wax crystal and retaining the dye stuil' in solution.

Having thus described my invention, it will be apparent that standardization systems and methods can be established for testing the oil content in waxes or in plant control work and other uses which may come within the scope oi the appended claims.

I claim:

1. The method of determining the oil content of waxes by the addition or an oil soluble and crystallizable dye stuil which is soluble in liquid wax and insoluble in crystallised wax, oom- 4 prising incorporating an oil-soluble dye in a liquid wax material, solidifying the wax, and determining the color change oi the dye.

2. The method of determining the oil content I oi waxes by an addition of a sudan dye characterized by a beta-naphthol group attached to another aromatic group by an azo linkage which is soluble in molten wax and insoluble in crystallized wax, comprising incorporating an oil-soluble sudan (we in molten wax, solidifying the wax, and determining the color change of the dye.

3. The method of determining oil content of waxes by an addition of anthraquinone derivative oil-soluble alizorin dye stuns which are soluble in molten wax and insoluble in crystallized wax, comprising incorporating an oil-soluble alizarin dye in molten wax, solidifying the wax. and determining the color efiect of the dye.

4. The method of determining the oil content of wax material in the nature of brown coal tar waxes and mineral oil waxes by the addition of coloring matter being a member of the group consisting of oil-soluble and orystallized-wax-insoluble sudan dye characterized by a beta-naphthol group attached to another aromatic group by an azo linkage and oil-soluble and crystallizedwax-insoluble anthraquinone derivative alizarin dye, comprising incorporating said coloring matter in melted wax in which the coloring matter is soluble, subsequently crystallizing the wax material to separate the coloring matter therefrom as a material insoluble in the crystallized wax material, and evaluating the eilect o! the coloring matter.

5. The method of determining the oil content oi wax material in the nature of brown coal tar waxes and mineral oil waxes by the addition of oil-soluble alizarin-irisolblue dye stun comprising incorporating the dye in melted wax in which the dye is soluble, subsequently crystallizing the wax material to separate the dye therefrom in which the dye is soluble, as a material insoluble in the crystallized wax material, and determining the eflect of the dye.

6. The method of determining the oil content of a wax sample by a comparative test, comprising adding a coloring agent being a member 01 the class consisting of oil-soluble and crystallizedwax-insoluble sudan dye characterized by a betanapthol group attached to another aromatic group by an azo linkage and oil-soluble and crystallized-wax-insoluble anthraquinone derivative alizarin dye in the proportion of 0.05 to 0.10% to molten wax, crystallizing the wax and comparing the samples coloring with a standard.

7. The method of determining the oil content of a wax sample by a comparative test comprising adding an oil-soluble and solidified-wax-insoluble crystallizable coloring matter in the proportion of 0.05 to 0.10% to molten wax, crystallizing the wax and comparing the sample's coloring with a standard.

B. The method of determining the oil content of waxes by the addition of an oil soluble crystallizable coloring material which is soluble in molten wax and insoluble in crystallized wax. comprisin dissolving the coloring matter in a liquid wax, solidifying the wax to exclude the coloring matter, and determining the coloring change.

9. The method of determining the purity 01' a waxy material by the addition of an oil-soluble and crystallized-wax-insoluble sudan red coloring agent characterized by a beta-napthol group attached to another aromatic group by an are linkage, comprising incorporating the coloring agent in liquid waxy material in which the coloring agent is soluble, subsequently crystallizing the wax material to separate the coloring agent from the crystalline wax, and determining the change of color in the coloring agent. i

10. The method of determining the wax content of a waxy composition by the addition of an oil-soluble coloring agent which is soluble in uncrystallized wax and insoluble in crystallized wax comprising incorporating in uncrystallized waxy composition an oil-soluble coloring matter, crystaliizing the wax to exclude the coloring matter, and determining the color efiect of the excluded coloring matter.

11. The method oi determining the wax content of a waxy composition by the addition of an oil- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Hickman Apr. 5, 1938 Number 

1. THE METHOD OF DETERMINING THE OIL CONTENT OF WAXES BY THE ADDITION OF AN OIL SOLUBLE AND CRYSTALLIZABLE DYE STUFF WHICH IS SOLUBLE IN LIQUID WAX AND INSOLUBLE IN CRYSTALLIZED WAX, COMPRISING INCORPORATING AN OIL-SOLUBLE DYE IN A LIQUID WAX MATERIAL, SOLIDIFYING THE WAX, AND DETERMINING THE COLOR CHANGE OF THE DYE. 